Our present invention relates to a continuous light-section or wire rod rolling train of the type which comprises between an intermediate rolling block or section and a dimensioning finishing block or section a variable path for the rolled product, i.e. the workpieces.
Continuous light-section or wire rod mills in which a variable path is provided between at least one intermediate rolling unit and the dimensioning finishing rolling unit which is followed by a cooling section and/or a temperature equalization section are known and allow better temperature control of the rolling operations and hence improvement of the mechanical properties of the rolled product. Indeed, special thermal treatments can be avoided and controlled temperature profiles can be ensured within the rolling lines.
In thermomechanical rolling, speeds in the finishing mills or stands and like requirements of the rolling line have generally resulted in a close proximity of the rolling stands, a need for heating the product to be rolled and high requirements for temperature control and heat dissipation before the wire rod or small structural shapes produced in the rolling operation reach the finishing rolls.
In the commonly owned U.S. Pat. No. 6,105,412 (DE 198 43 032) for a rolling mill for the continuous rolling of light-sections or wire rod, two paths are provided selectively for the rolled product between the intermediate rolling section and the dimensional finished rolling unit. In a first of these paths the workpieces are fed from the intermediate rolling stand to a finishing mill unit and a sizing mill unit located one behind the other and then to cooling sections before reaching a rolling stack collector. Upstream of the finishing and dimensioning mills, a branch or distributing guide and a cooling section are provided. The second path from this distributing guide also includes a cooling section, a finishing mill unit and a further cooling section with a loop forming a path segment between them and between the second path and a distributing guide leading the rolled product back to the first path upstream of the shear and the finishing and dimensioning mills thereof.
With this mill train, the possibility of varying the paths, the cooling and temperature equalization effects on the rolled product can satisfy some of the different requirements for rolling larger and smaller cross sections.
Another system is disclosed in EP 0 606 966 B1 in which the rolled product coming from the intermediate rolling bock can pass selectively over a branch guide to a line having cooling stretches and a finishing mill block or via further branching guides into a second line parallel to the first and equipped with a finishing mill block and cooling sections and then directly to the rolled product collector or via a distributing guide arrangement between the two lines back to the first.
It is the principal object of the present invention to improve upon the rolling mill systems described so that the working of the product to be rolled, together with the cooling and temperature equalization can be matched to the material characteristics over a substantially greater range and to enable a substantially greater variation in the products which can be rolled.
Another object of this invention is to provide a continuous light-section or wire rod rolling train of greater versatility, better process control and more effective temperature profile control for a wider variety of rolled products than has heretofore been the case.
It is also an object of this invention to provide an improved rolling mill for light-section rolled stock, small cross section structural shapes and wire or rod whereby drawbacks of earlier milled systems are avoided.
These objects are attained, in accordance with the invention by providing a multifunctional path between a conventional intermediate rolling block or unit and a dimensioning finishing rolling block or unit followed by a standard cooling and/or temperature equalization line and, in particular, by forming that multifunctional or multipath section in a particular manner.
More specifically, the object can be achieved with a continuous light-section or wire rod rolling train comprising at least one intermediate rolling unit, a dimensioning finishing rolling unit, a cooling section following the dimensioning finishing unit, a temperature equalization section following the cooling section, and a multi-functional variable path section between the intermediate rolling unit and the dimensioning finishing rolling unit, the multi-functional variable path section comprising three substantially parallel processing lines including:
a first line connected to an output side of the at least one intermediate rolling unit and including in succession an intermediate rolling block, a first distributing guide, at least one cooling section or temperature equalization section and a second distributing guide having one outlet delivering workpieces to the dimensioning finishing rolling unit;
a second line having at least one intermediate rolling block and delivering workpieces to the second distributing guide; and
a third line connected to another outlet of the second distributing guide and provided with at least one cooling section,
the rolling train further comprising:
a first 180xc2x0-loop-forming path segment connecting an outlet of the first distributing guide to the third line;
a third distributing guide connected to the first 180xc2x0-loop-forming path segment in the third line and a fourth distributing guide connected to the third distributing guide in the third line;
a second loop-forming path segment connected between the other outlet of the second distributing guide and the third line;
a third 180xc2x00-loop-forming path segment connected between one outlet of the fourth distributing guide and the second line between the intermediate rolling block and the cooling section thereof; and
a fourth 180xc2x0-loop-forming path segment connected between the third line and the second line upstream of the intermediate rolling block thereof whereby the workpieces are selectively directable from the first line to the dimensioning finishing rolling unit without traveling over the second and third lines and to the dimensioning finishing rolling unit after traveling over all or part of the second and third lines.
Thus the rolling train downstream of the at least one intermediate rolling unit has three distinct lines of which the first is provided upstream of the rolled product collecting device, usually located at or immediately upstream of the dimensioning finishing rolling unit, with a distributing guide which is capable of accepting rolled product form the second line and delivering rolled product to the third line.
Upstream of that three-way distributor, the first line can include a first intermediate rolling block and, downstream thereof, another distributing guide capable of sending the rolled product to the third line at an intermediate location along the length thereof via a 180xc2x0 loop forming segment or to cooling temperature equalization sections leading to the three-way distributing guide. The latter can have another loop forming segment connecting an outlet of that guide with the third line upstream of a cooling section and the further distributing guides thereof which selectively transmit the rolled product either through a loop to the second line or further along the third line where, via a 180xc2x0 loop-forming section, it meets the first line at the upstream end thereof.
With this combination of the three arm distributor and other distributing guides and loop forming (preferably 180xc2x0) path segments, the invention can ensure travel of the rolled product via the first line from the intermediate rolling block thereof through the cooling section and temperature equalization section thereof directly to the product collector or the dimensioning finishing rolling unit or past the cooling and temperature equalization sections of the first line to the third line and from there through all or part of the second line which can have a further intermediate rolling block and one or more cooling sections to the dimensioning finishing rolling block and the rolled product collector.
Via the three arm distributor, the rolled product can be delivered to the third line to the second line downstream of its intermediate rolling block.
As a result of the versatility, wire rod thicknesses of 5.0 and 11.0 as well as 11.0 to 22.0 mm can be rolled with intensive cooling, excellent temperature equalization and low inlet, outlet and finishing rolling temperatures in the intermediate rolling blocks and the dimensioning finishing block while the cooling can be reduced. It is also possible to operate as desired with higher inlet and finishing temperatures for those products which can benefit from it.